1. Field of the Invention
The field of the invention is data processing, or, more specifically, methods, systems, and products for content addressable data storage and compression for semi-persistent computer memory for a database management system.
2. Description of Related Art
Content addressable storage, sometime called associative storage, is a kind of computer memory storage in which items of data are stored and retrieved by analysis of their content rather than by fixed memory addresses or locations. Traditional approaches to content addressable storage confront a dilemma: content addressable methods can be efficient in terms of CPU utilization if they use fixed memory block sizes, but using a fixed memory block size is an inefficient use of underlying storage media. Traditional methods of content addressable storage also typically do not provide for data compression, although, in terms of efficient use of underlying storage media, it would be beneficial if they did.
Hard drives are almost always underutilized. Performance for database management systems can be improved by providing semi-persistent storage based upon underutilized disk drive memory, that is, memory not allocated to any file or inode in a traditional file system. There are at least two classes of affected memory storage requirements for database management systems: persistent storage of critical data such as data tables, configuration information, and the like, and semi-persistent storage of optimization data such as database indices, temporary query storage, temporary query results storage, input/output caches, and so on. In order to insure that needs are met for the first class of storage, the second class of storage is often given very finite storage limitations that do not correspond to the amount of free space that may actually be available. There is therefore an ongoing need for improvement in the area of semi-persistent memory storage for database management systems.